FILE - In this Jan. 5, 2017, file photo, an exhibitor demonstrates a drone flight at CES International in Las Vegas. On Wednesday, May 9, 2018, federal transportation officials announced 10 sites for a three-year drone program aimed at increasing government and commercial use of unmanned aircraft. The sites are located in Oklahoma, California, Nevada, North Dakota, North Carolina, Kansas, Alaska, Virginia, Tennessee and Florida. less

FILE - In this Jan. 5, 2017, file photo, an exhibitor demonstrates a drone flight at CES International in Las Vegas. On Wednesday, May 9, 2018, federal transportation officials announced 10 sites for a ... more

Photo: Jae C. Hong, AP

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FILE-- C.J. Beathard #3 of the San Francisco 49ers is tackled by Michael Bennett #72 and Nazair Jones #92 of the Seattle Seahawks at Levi's Stadium on November 26, 2017 in Santa Clara, Calif. On the Sunday after Thanksgiving, Sacramento resident Tracy Mapes drove to Santa Clara, flew a drone over Levi's Stadium and dropped a payload of leaflets espousing his conspiracy theories over the San Francisco 49ers-Seattle Seahawks game.

FILE-- C.J. Beathard #3 of the San Francisco 49ers is tackled by Michael Bennett #72 and Nazair Jones #92 of the Seattle Seahawks at Levi's Stadium on November 26, 2017 in Santa Clara, Calif. On the Sunday

On the Sunday after Thanksgiving, Sacramento resident Tracy Mapes drove to Santa Clara, flew a drone over Levi's Stadium and dropped a payload of leaflets espousing his conspiracy theories over the San Francisco 49ers-Seattle Seahawks game.

He then headed across the Bay to the Oakland Raiders game intent on doing the same.

A year ago this month, a San Diego bartender crashed his drone into a fan at the Padres' Petco Park.

While Mapes was later arrested and the bartender was tracked down and fined, team security and local police were unable to stop the flights - whether with high-tech jammers or other means - for fear of violating federal law.

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"Federal law prohibits local law enforcement from disarming or disabling drones, even if they are in restricted airspace," said National Football League Senior Vice President Jocelyn Moore. "This loophole in federal law puts the safety and security of millions of sports fans and eventgoers at risk."

The same prohibitions on intercepting communications or disabling aircraft also apply to the FBI, Department of Homeland Security and most other federal agencies.

The Trump administration on Wednesday tapped 10 pilot projects, from mosquito control in Florida to food delivery in California, that it hopes will offer lessons for how to sharply expand drone use nationwide. But major league teams are increasingly anxious about the more than one million drones government officials estimate are already in use. They are asking Congress to give local law enforcement permission to seize or reroute drones flying over stadiums. And they are trying to get in a position to protect themselves.

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The families that own the New York Mets have invested in a Silicon Valley firm, Airspace, that uses artificial-intelligence driven drones that can find and capture other drones. Farzam Kamel, a partner at Sterling VC, an investment arm of the Wilpon and Katz families, said they are working to address the "very rare but devastating threat that can come."

"Knock on wood that hasn't really happened in our market or in the U.S. But it would be foolish to think it won't or it can't," Kamel said.

Citi Field, home of the Mets, is a good place to demonstrate the technology, Kamel said, given the complex environment and numerous variables at play. It's near LaGuardia airport, so team officials must work closely with the Port Authority of New York and New Jersey, along with the Federal Aviation Administration. The New York Police Department also is very focused on the issue, given the city's high profile, he said.

"So do we wait until something devastating happens before we get realistic about it? Or are we practical and plan accordingly now, so that we can avoid that outcome?" Kamel asked. "Or when something does happen, if it's at a venue that's not deploying a solution that can deal with that threat, at least there's a viable solution out there that can be rapidly deployed across venues when it's needed."

The Padres asked engineers from Airspace to recreate the bartender's ill-fated flight over their stadium. Executives say they were able to detect the approaching drone from afar and nab the intruder midair with a Kevlar net.

"Our kids are going to be in those stadiums," Airspace chief executive Jaz Banga said.

Team officials are impatient, saying the problem has been clear for years.

"There's technology out there that we can use, and we do use," said Cathy L. Lanier, the NFL's senior vice president of security, including tools to detect when drones are flying nearby. "But the technology we really need is not yet legal to use."

The Department of Defense was freed over the past two years, in certain cases, from prohibitions against intercepting electronic communications and "sabotaging" aircraft, in order to address drone threats.

The Trump administration has proposed giving the departments of Homeland Security and Justice similar powers.

But Lanier, the former D.C. police chief, said that proposal "doesn't help us, because I don't think I'm going to get a Secret Service or DHS agent to 256 games a year" to defend NFL venues against drones. The FAA imposes temporary flight restrictions near stadiums during games, but they are routinely ignored.

Said Lanier: "80,000 people in a stadium is a critical thing to protect." The incident at the 49ers game was just the latest reminder. "There are a lot of other things that could have been delivered that way that could have been a lot worse."

Still, allowing widespread use of counter-drone technologies is fraught with unresolved issues and, some say, comes with its own set of dangers.

Last year, the Trump administration sought counter-drone powers for numerous federal agencies, but the request was rejected based on bipartisan concerns in Congress that it was too broad.

Some legal scholars say allowing government agencies to intercept communications related to drones could have implications for civil liberties.

The FAA fiercely guards its control of U.S. airspace and officials there say such consistency contributes to the nation's stellar safety record. Allowing aircraft - in this case drones - to be interfered with in ever more places raises safety issues, some aviation experts said.

There also are concerns that stray signals from anti-drone defenses, depending on how they're used, could interfere with cellphones or radios, possibly affecting heart monitors or airplane navigation equipment.

Still, given the threats, a number of private firms are taking legal risks, calculating that the consequences of breaking the law would be less severe than being attacked.

Some stadiums are "playing very close to the line, maybe over it" by deploying technologies that can interfere with an operator's ability to control their drone, according to an administration official who was not authorized to speak publicly.

FBI director Christopher A. Wray, testifying before a senate panel in September, noted terrorists' use of drones overseas and said "I think the expectation is it's coming here imminently."

Lanier, who had to balance competing interests as a big city police chief, says there is understandable debate about allowing counter-drone measures that are effective but don't cause wider disruptions. "But we have to get it together sooner or later," she said.

"Drones aren't even new. The new technology now is autonomous vehicles. We're already behind the curve by a couple generations," Lanier said.

The Dallas Cowboys' and Texas Rangers' stadiums, as well as those at the Universities of Nebraska, Missouri, Texas and Kentucky have all had unwelcome visits from drones, according to FAA records obtained under a public records request. One operator flew his drone "in close proximity" to four parachutists landing at the University of Kentucky. He later lost control and crashed the device inside the stadium; he was fined $2,200.

One problem, authorities say, is they can't tell friend from foe.

The FAA is pushing for a requirement that all drones have the electronic equivalent of a license plate, to allow for remote identification and tracking. That would require changing an existing ban on new FAA regulations on the more than one million drones deemed "recreational."

The House passed a bill last month outlawing guns on drones, though some in Congress questioned whether that too would be undermined by existing law.

Mapes posted videos showing test runs of his leaflet drops in the days before he headed for the 49ers game. "I had bombed the Sacramento Area, Capitol TV Stations for 1 month prior to the 2 NFL games in November," he wrote in an exchange of messages with The Washington Post.

His fliers were emblazoned with a stark red "X," an American flag, and his name. He warned that "Prostitutes and Felons have been Infiltrated into America's Newsrooms and Local Municipal Politics," as well as the Oval Office.

"These leaflets were passed out in quite a scary way for us," Santa Clara police Capt. Wahid Kazem said. "We're not only worried about what is coming down from the sky from this thing. We're worried about how people are reacting to that in the seats."

Even spooking a tiny fraction of the crowd could lead to tragedy, he said.

Mapes drove off toward the Oakland Coliseum, where he hoped for a repeat performance. The NFL went on alert, warning other teams still to play that day.

Authorities found Mapes near the coliseum, and he was later charged with a misdemeanor. Federal officials opened an investigation, which continues.

Mapes once worked in news video and now lives in an 8'x7' shed after his rent was raised, he said. He plans to continue his "campaign to turn this God damned country back into some form of sanity that I might recognize from childhood, before I run out of breath."